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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2009-04-08 to 2009-05-11
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
GLP compliance:
yes
Specific details on test material used for the study:
Batch No.: 20090226
Purity: 99.38%
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of activated sludge: 15 sites in Korea, including 7 rivers, 5 domestic sewage plants, 3 industrial wastewater treatment plants
- Laboratory culture: No data
- Method of cultivation: No data
- Storage conditions: No data
- Storage length: 1 month
- Preparation of inoculum for exposure: No data
- Pretreatment: No data
- Concentration of sludge: No data
- Initial cell/biomass concentration: No data
- Water filtered: No data
- Type and size of filter used, if any: No data
Duration of test (contact time):
28 d
Initial conc.:
100 other: ppm (w/v)
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
TEST CONDITIONS
- Composition of medium:
-- A: K2HPO4 2.175 g, KH2PO4 085 g, Na2HPO4.12H2O 4.46 g, NH4Cl 0.17 g, dissolved in deionised water and made up to 100 mL. pH adjusted to 7.2
-- B: MgSO4.7H2O 2.25 g, dissolved in deionised water and made up to 100 mL.
-- C: CaCl2 2.75 g dissolved in deionised water and made up to 100 mL
-- D: FeCl3. 6H2O 0.025 g, dissolved in deionised water and made up to 100 mL. pH adjusted to 7.2

- Volume of activated sludge: 6 mL
- No. of viable cells > 1E+07 cells/mL
- Temperature: 25 °C ± 1 °C

MICROBIAL DEGRADATION
- Bottle 1 (abiotic control): Deionised water 150 mL, test substance solution 15 mg (100 ppm level)
- Bottles 2, 3, 4 (test item): Basal culture medium 144 mL, activated sludge 6 mL, test substance solution 15 mg (100 ppm level)
- Bottle 5 (activity control): Basal culture medium 144 mL, activated sludge 6 mL, aniline 15 mg (100 ppm level)
- Bottle 6 (inoculum blank): Basal culture medium 144 mL, activated sludge 6 mL.
Reference substance:
aniline
Key result
Parameter:
% degradation (O2 consumption)
Value:
54.1
Sampling time:
28 d
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
In a study to OECD guideline 301C (Ready Biodegradability: Modified MITI Test (I)), it was found that the substance was not readily biodegradable.
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2010-04-23 to 2010-07-22
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 302 C (Inherent Biodegradability: Modified MITI Test (II))
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of activated sludge: not less than 10 places throughout the country
- Method of cultivation: The sludge samples collected from sampling sites are mixed with the same volume by stirring in a single container, and the mixture is allowed to stand. Floating foreign matter is removed and the supermatant is filtered through No.2 filter paper. The filtrate is adjusted to pH 7.0 with sodium hydroxide or phosphoric acid, transferred into a culture tank and aerated for 23.5 h.
- Storage conditions: 25±1°C
- Storage length: 1 month
Duration of test (contact time):
28 d
Initial conc.:
30 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium:
-- A: KH2PO4 8.5 g, K2HPO4 21.75 g, Na2HPO4.2H2O 33.4 g, NH4Cl 1.7 g, dissolved in water and made up to 1L. pH of solution was 7.2.
-- B: CaCl2 27.5 g, dissolved in water and made up to 1L.
-- C: MgSO4.7H2O 22.5 g, dissolved in water and made up to 1L.
-- D: FeCl3. 6H2O 0.25 g, dissolved in water and made up to 1L.
Mix 1 mL of solutions A,B,C,D with 800 mL water and then make up to 1L.

MICROBIAL DEGRADATION
- Bottle 1: Deionised water 1000 mL, test chemical 30 mg
- Bottles 2, 3, 4: Basal culture medium 1000 mL, activated sludge 100 mg (dry basis), test chemical 30 mg
- Bottle 5: Basal culture medium 1000 mL, activated sludge 100 mg (dry basis), sodium benzoate 100 mg
- Bottle 6: Basal culture medium 1000 mL, activated sludge 100 mg (dry basis)
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
80.5
Sampling time:
28 d
Details on results:
The viability of the inoculum and validity of the test were supported by the results of the reference substance, sodium benzoate. The average percent degradation on days 7, 14, 21 and 28 were 83%, 88.8%, 91.7% and 93.3%, respectively, which fulfilled the criteria for a valid test.
Based on the ThOD of the test item (2.67 mg O2/mg), the average percent degradation of the test item on days 7, 14, 21 and 28 was 43.6%, 75.5%, 79.4% and 80.5%, respectively.
Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
In a study to OECD guideline 302C (Inherent Biodegradability: Modified MITI Test (II)), it was found that the average percent degradation of the test item on days 7, 14, 21 and 28 was 43.6%, 75.5%, 79.4% and 80.5%, respectively. The substance was considered to be inherently biodegradable.

Description of key information

Not readily biodegradable (OECD 301C).

Inherently biodegradable (OECD 302C).

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

In a study to OECD guideline 301C (Ready Biodegradability: Modified MITI Test (I)), it was found that the

percentage biodegradation of test item observed by BOD meter was 54.1% and GC analysis was 92.7% after 28 days. The test substance is therefore not considered to be readily biodegradable.

In a study to OECD guideline 302C (Inherent Biodegradability: Modified MITI Test (II)), it was found that the average percent degradation of the test item on days 7, 14, 21 and 28 was 43.6%, 75.5%, 79.4% and 80.5%, respectively. The substance was considered to be inherently biodegradable.